Cushion valve for air cylinders



July 10, 1956 BECKER 2,753,849

CUSHION VALVE FOR AIR CYLINDERS Filed Dec. 28, 1950 I Ina/6212?? 0567? Z15 ecler 2,753,849 CUSHION VALVE FOR AIR CYLINDERS Robert E. Becker, Logansport, Ind., assignor to Logansport Machine Co., Inc.,.a corporation of Indiana Application December 28, 1950, Serial No. 203,045

2 Claims. (Cl. 121-38) My invention relates to improvements for cushion valves for air cylinders and has for one object to provide in association with an air cylinder a control valve and a source of compressed air supply, means for controllably and adjustably cushioning the end of the stroke.

Other objects will appear from time to time throughout the specification and claims.

My invention is illustrated more or less diagrammatically in the accompanying drawings wherein only the cushion valve itself is shown in detail.

Figure 1 is a flow diagram showing the cushion valve in side elevation and associated parts in longitudinal cross section;

Figure 2 is a longitudinal cross section of the cushion valve and Figure 3 is a section taken on line 3-3 of Figure 2.

Like parts are indicated by like characters throughout the specification and drawings.

A is a cylindrical casting open at one end and closed at the other end by an integral apertured head B, the open end being closed by a removable apertured head C. The head B is ported at 1 for connection with one end of a power cylinder D by means of the duct 21. The head C is ported at 3 for connection with the other end of the power cylinder through the duct 22 so that there is a connection to the cylinder on each side of the power piston 23, the power piston applying power through a piston rod 24 to any suitable piece of machinery. The port 2 in the head C is connected by a duct 25 to the port 26 of the master control valve E.

With the parts in the position shown, air enters the control valve from a suitable source of supply through the duct 29, passes through the port 26, the duct 25, the port 2 into the chamber 30 in the removable cushion valve head, thence through the port 3, duct 22 to the head end of the cylinder D applying pressure to the piston 23 and moving it to the right. Meanwhile air leaks through the orifice 5 controlled by the adjustable metering valve 6 thence through the duct 7 to the interior of the cushion valve A into the chamber 8. The check valve disc 9 is held to the right in seated position by the pressure of air in chamber 30, the check valve structure 10 being so arranged as to permit such movement of the check valve disc 9.

As pressure builds up in the chamber 8, the piston 11 with its packing rings 12 is forced toward the right until the valve seat 13 surrounding the port 4 in the cylinder head B is contacted by the valve disc 14 on the piston.

Until such contact is made the movement of the piston 23 under the pressure of the air expels air from the cylinder through the duct 21, port 1, chamber 18 in front of the piston 11 through the port 4, duct 27, port 28, discharged to atmosphere from the valve E through the port 31. Thus there is not control or cushioning of movement of the piston 23 except that furnished by the master control valve E. However, as soon as the valve disk 14 engages the seat 13, the situation changes, theair being expelled by the piston 23. It now travels from the nited States Patent 0 port 1 through the annular passage 32 around the valve seat 13 through the duct 15 and aperture 17 controlled by the metering needle valve 16, thence through port 4, duct 27, port 28, valve E to atmosphere at 31. Thus the setting of the needle valve 6 controls the time at which the needle valve 16 goes into action and the setting of the needle valve 16 controls the rate at which the piston 23 is cushioned by the residual air at the end of its stroke to the right.

When the valve E is reversed and air under "pressure from 29 passes through port 28, duct 27, port 4 it immediately moves the piston 11 to the left permitting free flow of air from chamber 18, port 1, duct 21 to the right hand side of the piston 23 in cylinder D. Under these circumstances the piston 11 is moved back to its starting position, at the same time the air is expelled from the left hand end of the cylinder D passing through the duct 22, port 3, chamber 39, port 2, duct 25, port 26, valve E, exhaust to atmosphere at 31. The needle valve 6 has no eifect on the return movement of the piston 11 because as soon as the piston begins to move the check valve 9 is unseated to permit free flow of air from in front of the left hand face of the piston 11.

If it is desired to cushion both ends of the power piston stroke, a separate cushion valve must be inserted for each end. If it were desired to cushion the piston on the other movement, then the ducts 21 and 22 would merely be reversed but a separate cushion valve is required for each separate cushioning action. However, the cushion valve shown does make it possible to adjust not only the rate or effect of cushioning but also the position in the stroke when cushioning starts. The air supplied to the valve E will always be of substantially uniform pressure and the resistance to movement of the piston 23 will normally be substantially uniform. Thus by setting the needle valve 6 the rate at which air leaks into the chamber 8 will remain substantially constant and so the movement of the piston 11 will be substantially constant. Once the piston 11 is seated the cushion depends entirely on the rate at which the needle valve 16 permits air to leak out through the port 17 and an adjustment of the needle valve micrometrically controls this rate.

I claim:

1. In combination in a cushion valve assembly, a power cylinder having a power piston mounted for reciprocation therein, a master control valve having a plurality of control ports, a source of high pressure fluid connected to the master control valve, fluid connections between the master control valve and the power cylinder so that each side of the power piston can be put in communication with the source of high pressure fluid while the other side is vented, and a cushion valve unit in the fluid connections, including a cushion valve cylinder and piston, the cylinder being connected at each end to the fluid connections, a controllable vent between one side of the cushion valve piston and one fluid connection to regulate the movement of the cushion valve piston in one direction when the source of high pressure fluid is placed in communication with the said one side of the cushion valve piston and the other side is vented by the master control valve, a valve carried by the cushion valve piston to prevent flow of fluid from the power cylinder, a metering passage by-passing said valve on the cushion valve piston, and means including a check valve bypassing said controllable vent operative when the high pressure source is placed in communication with the other side of the cushion valve piston and the said one side is vented by the master control valve for freely returning the cushion valve piston in the other direction at a uniform rate.

2. In combination, a power cylinder having a piston mounted for reciprocation therein, a cushion valve cylinder, a connection between each end of the cushion valve cylinder and an end of the power cylinder, a master control valve having a plurality of control ports, means for supplying fluid under pressure to the master control valve, a connection between the master control valve and both ends of the cushion valve cylinder, a cushion valve piston mounted for reciprocation in the cushion valve cylinder, flow control means for controlling the flow of fluid under pressure on its Way to the power cylinder to displace the cushion valve piston in the cylinder, a valve carried by the cushion valve piston adapted to prevent flow of fluid from the power cylinder, a metering passage bypassing said valve, and means including a check valve bypassing said flow control means operative upon reversal of fluid pressures to freely return the cushion valve piston to starting position at a uniform rate.

References Cited in the file of this patent UNITED STATES PATENTS Steedman Jan. 8, 1907 Mock Apr. 16, 1912 Hand June 7, 1932 Hartley et a1 Aug. 15, 1950 Davies Feb. 13, 1951 Ring Nov. 18, 1952 FOREIGN PATENTS Germany Dec. 29, 1933 

